Diaphragm-equipped acoustic apparatus



Sept. 22, 1931. M. BERNARD 1,824,590

DIAPHRAGM EQUIPPED ACOUST IC APPARATUS Filed June 7. 1929 INVENTORMARCEL BERNARD ATTORNEY l atented Sept. 22, 1931 I MABCEL BERNARD,PARIS, FRANCE DIAPHRAGM-EQUIPPED ACOUSTIC APPARATUS Application filedJune 7, 1929, Serial No. 369,076, and in France June 14, 1928.

This invention relates to sound generating or receiving apparatus suchas loudspeakers. More particularly it relates to apparatus of thisnature wherein the vibrating diaphragm is of large dimensions.

The object of the invention consists in providing an improved suspendingmeans for such large diaphragms which, among other advantages, furnishesthe tensional 1 forces insuring rigidity of the diaphragm and, at thesame time, furnishes the elastic forces tendin to restore the diaphragmto its position 0% rest.

The invention will be better understood by reference to the accompanyingdrawings and the description thereof covering an approved form of thebasic idea of the invention. In the drawings,

Figure 1 illustrates diagrammaticall a section through the diaphragmsuspen ing' means;

Figure 2 illustrates a force diagram for the suspending means; and

Figure 3 illustrates the spring member shown in Figure 1 which isconnected between the diaphragm and the suspending member.

As shown in Figure 1, a tympanum 1 preferably of a conical shape, isprovided circumferentially witli'a cylindrical border or edge 2. Theborder 2 may be provided by giving a suitable shape to the sheet oflamina forming the tympanum or it may be formed from a separate piece ofmaterial and attached to the edge of the tympanum in any well knownmanner as by gluing or cement ing. A spring member 3 is arranged topress upon the inner face of the cylindrical border or rim 2. Thisspring which, for example, may consist of a lamina of metal, is providedwith a suitable curvature so that it may exert an oblique force oreffort upon the axis of the tympanum when it is depressed by itsinsertion under the border or rim of the tympanum.

In Fi ure 2 this oblique force is illustrated at F. %t consists of aradial component f and an axial component f The radial force orcomponent i, contributes to the insurance of rigidity of the diaphragmby its being tensioned, whereas, the axial force or component f,contributes to overcoming the counteraction of the motor or drivingelement until the tympanum has been restored to its position ofequilibrium.

In order to acoustically insulate the tympanum from the spring member 3a layerof insulating material such as felt, soft rubber, etc. isinterposed between these two elements.

In the embodiment illustrated by Figure 1 a band of felt indicated byreference char- 6o, acter 4, is bent back, or crimped about thecylindrical rim 2 of the tympanum.

Thespring members indicated at 3 are provided at intervals along theperiphery of the tympanum. No particular spacing is re- 05 quiredbetween the spring-like members and the number used may vary with thesize of the tympanum, the material from which the spring members aremade and various other structural details. If desired, they may be drawnfrom one piece of sheet metal conveniently cut or stamped. Figure 3indicates such an arrangement in which the spring member consists of arim of metal 5 with a group of four springs. The spring 3 in F igure 1may be regarded as a out along an axial plane ab in Figure 3.

The metal rim 5 may be secured to a supporting member 6 in any wellknown manner. The supporting member 6 may consist of a planar wall orsurface such as a baflie board or the front of a cabinet, and it isprovided with a circular opening of suitable size for the freepropagation and issuance of the sounds given off by the tympanum. Anywell known form of motor or driving means may be installed so as to besupported in any approved manner, such as by suitably arranged arms,from the supporting member 6.

The notches in the metallic rim 5 or the gaps or openings between theseparate springs 3 are preferably covered by means of an elastic or feltband in such a way that they will not impede the operation of thedevice.

, If desired, the loudspeaker may be formed by arranging two diaphragmsin opposition with the peak or apex of the diaphragms arranged so as tobe driven or impelled by the same driving means. The diaphragms 100 maybe of either the same or of different dimensions. V V V Various othermodifications may be made Without departing from the spirit of the in-Vention and itis desired that the present invention be limited only bythe scope of the claims. V

I claim 1; Acoustic apparatus comprising a dia-.f phragm, a rim on saiddiaphragm presenting a cylindrical surface, a'support for the diaphragm,and metallic elements fixed to the support and bearing elasticallyagainst the interior face of said cylindrical surface.

2. Acoustic apparatus comprising a diaphrag'm, a rim on said diaphragmpresenting a cylindrical surface, a support for said diaphragmand ametallic rim furnished with teeth and fixed to the support, said teethbear- 'ing-elasti'cally against the inner face of said cylindricalsurface.-

3; Acoustic apparatus comprising a-diaphragm, a rim on said diaphragmpresenting a cylindrical surface a supporting member, metallic meansfixedto the supporting memher and bearing elastically against the innerface of said cylindrical surface, and an elas- V tic sheetinterposedbetween said surface and the metallic means.

'MARGEL BERNARD,

